Key Engineering Materials Vol. 1045

Abstract: Surface modification of metallic materials to impart antibacterial properties has attracted significant attention for practical applications in biomedical and industrial fields. This study aims to characterise the antibacterial surface textures of Ti alloys (Ti-6Al-4V) and investigate their relationship with water repellency, bio-adhesion resistance, and antibacterial performance. Two distinct surface textures were fabricated using chemical (acid treatment for 5 and 20 min) and physical methods (tensile testing). Antibacterial tests revealed 41.6%, 14.6%, and 31% reductions in the viable bacterial counts for the 5-minute acid-treated, 20-minute acid-treated, and tensile-tested samples, respectively, compared to untreated controls. Contact angles of 100.9°, 96.1°, and 79° were observed, indicating varying degrees of water repellency. The acid-treated samples exhibited reduced bio-adhesion, whereas the tensile-tested samples showed increased bio-adhesion. These findings suggest that the surface morphology that inhibits bacterial aggregation is the primary factor contributing to antibacterial properties. Although water repellency and bio-adhesion resistance are often associated with antibacterial surfaces, they serve as functional correlations rather than direct determinants. The surface texture developed in this study exhibited a symmetrical vertical height distribution with Sa = 0.24 µm and featured flat valley regions, rendering it highly suitable for antibacterial applications and promising for use in biocompatible environments.

Abstract: A mild, solvent-free method for the encapsulation of curcumin in chitosan–carrageenan nanoparticles was developed by introducing curcumin after polyelectrolyte complex formation but before crosslinking with sodium tripolyphosphate (STPP). This approach was carried out to promote effective encapsulation without interfering with the electrostatic interactions essential for nanoparticle formation. FTIR analysis confirmed the presence of electrostatic and hydrogen bonding interactions among curcumin, chitosan, and carrageenan. Atomic force microscopy (AFM) revealed an increase in nanoparticle size upon curcumin loading, while transmission electron microscopy (TEM) provided morphological evidence supporting encapsulation within the nanoparticle matrix. These results confirm the successful encapsulation of curcumin into chitosan–carrageenan nanoparticles using a strategy that preserves nanoparticle integrity while minimizing curcumin loss. The resulting system presents a promising, eco-friendly platform for curcumin delivery with broad potential in pharmaceutical, nutraceutical, packaging, and food-related applications.

Abstract: Aluminium has become a cornerstone of sustainable architectural design due to its lightweight properties, structural strength, corrosion resistance, and high recyclability. However, its primary production remains energy-intensive and a major contributor to greenhouse gas (GHG) emissions. This study presents a comparative Life Cycle Assessment (LCA) of commonly used aluminium alloys in architectural components, evaluating them across key stages—production and end-of-life—based on energy consumption, emissions, and recyclability. The analysis covers 3000, 5000 and 6000-series alloys, as well as recycled, anodized, and coated variants. The study contributes a parameterized LCA-based framework to support sustainable material selection in façade and structural design. It highlights the importance of incorporating recycled content, optimizing alloy use based on application, and adopting circular economy strategies such as closed-loop recycling. These findings offer practical guidance for architects, engineers, and policymakers striving toward low-carbon, net-zero building goals.

Abstract: The aim of this study is to analyze the mechanical and physical properties of refractory bricks produced via geopolymerization using volcanic ash. Volcanic ash was combined with 12 M sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) as activators, with a liquid-to-solid ratio of 0.2. Two brick prototypes were produced: a cylindrical specimen for testing compressive strength and water absorption, and a rectangular prism for analyzing thermal conductivity. The bricks were calcined at 600°C and 800°C, showing favorable performance compared to well-known commercial refractory bricks. Cylindrical specimens calcined at 600°C reached an average compressive strength of 5.51 MPa, while those calcined at 800°C averaged 6.60 MPa—more than double the 2.80 MPa of commercial bricks. The average density of the specimens at both temperatures was similar, around 1.58 g/cm³, significantly higher than the 0.95 g/cm³ of commercial counterparts. Moreover, the average thermal conductivity of the geopolymer bricks was 0.008 W/m·K, indicating superior insulating properties compared to the 0.39 W/m·K of commercial refractory bricks. These results demonstrate optimal properties in refractory bricks made from geopolymer-based volcanic ash.

Abstract: Steel is the most used material for concrete reinforcement; however, it performs poorly in aggressive environments (e.g. coastal areas) owing to corrosion (moisture and chlorides). This study aims to analyse the tensile strength of steel and glass fibre-reinforced polymer (GFRP) bars through laboratory testing to assess their feasibility and application in construction. Steel bars were tested by ASTM E8/E8M–22, obtaining values of 606.61 MPa (Ecuador) and 676.46 MPa (Peru), whereas GFRP bars were tested following ASTM D7205/D7205M–21 (1,000 MPa). The analysis indicated that GFRP bars offer structural advantages (suitable for elements in coastal zones with low to moderate seismic activity), environmental benefits (lower CO₂ emissions during production), and enhanced durability (corrosion resistance).

Abstract: Recently, the petroleum-based leather is focused for constituent material of wall in luxury architecture. This study examined the effect of repair processing on energy absorption of pre-crack-initiated leather for long-term use of products. Constituent materials at front and back sides of leather were, respectively, polyurethane and polyester. Tensile tests of non and pre-crack-initiated leather were conducted under constant temperature and humidity room. The crosshead speed was 100 mm/min. The repair processing was conducted by a hot-press molding method. The crack length was 4 mm. The patch size was 10 mm long and 10 mm wide. The following conclusions were obtained. Typical load-displacement curves of all leathers became nonlinear. The energy absorption of non-crack-initiated leather was higher than that of repaired leather. After some repair processing, the energy absorption of the repaired leather at bonding between polyester (Patch) and polyurethane showed the maximum value. But the fiber pull-out on fracture surface of repaired leather at bonding between polyester (patch) and polyurethane was found during tensile test. The crack initiation depends on energy absorption of leather. Therefore, the energy absorption of pre-crack-initiated leather was property affected by stress distribution and adhesion property at the repair area.